Bacterial pathogens response

Choi H.W. Kim Y.J. Lee S.C. Hong J.K. Hwang B.K. (2007) Hydrogen peroxide generation by the pepper extracellular peroxidase CaP02 activates local and systemic cell death and defense response to bacterial pathogens / / Plant Physiology. V. 145. P. 890-904. 

Acute pharyngitis presents a diagnostic and therapeutic dilemma. The majority of sore throats are caused by a variety of viruses fewer than 20% are bacterial and hence potentially responsive to antibiotic therapy. However, antibiotics are widely prescribed and this reflects the difficulty in discriminating streptococcal from non-streptococcal infections clinically in the absence of microbiological documentation. Nonetheless, Strep, pyogenes is the most important bacterial pathogen and this responds to oral penicillin. However, up to 10 days treatment is required for its eradication fixm the throat. This requirement causes problems with compliance since symptomatic improvement generally occurs within 2-3 days. 

If conventional treatment fails, unresolved diaper rash can also lead to secondary bacterial infections. Staphylococcus aureus and streptococci are the most likely pathogens responsible for these infections and require treatment with systemic antibiotics.3 37 While topical protectants may be used as an adjunct in treatment, suspected bacterial infections should always be referred to a physician for accurate diagnosis and the selection of an appropriate antibacterial regimen.34 Figure 62-7 shows a useful algorithm for the effective treatment of diaper dermatitis. 

O Osteomyelitis is an infection of the bone that is associated with high morbidity and increased health care costs. The inflammatory response associated with acute osteomyelitis can lead to bone necrosis and subsequently chronic infections. Bacterial pathogens, particularly Staphylococcus aureus, are the most common microorganisms implicated in these infections. Diagnosis and treatment are often difficult due to the heterogeneous... 

There are three major hallmarks of Pb-induced immunotoxicity (1) Pb can dramatically suppress the Thl-dependent DTH response, as well as production of associated Thl cytokines (2) Pb can dramatically elevate production of IgE while increasing production of Th2 cytokines such as IL-4 and (3) Pb can impair the production of new macrophages and shift existing macrophage populations into a hyper-inflammatory response phenotype that promotes tissue inflammation but, ironically, is not particularly effective against bacterial pathogens. 

Fritsche TR, Rhomberg PR, Sader HS, Jones RN. (2008) Antimicrobial activity of omiganan pentahydrochloride tested against contemporary bacterial pathogens commonly responsible for catheter-associated infections. J Antimicrob Chemother 61 1092-1098. 

Antimicrobial agents are frequently used before the pathogen responsible for a particular illness or the susceptibility to a particular antimicrobial agent is known. This use of antimicrobial agents is called empiric (or presumptive) therapy and is based on experience with a particular clinical entity. The usual justification for empiric therapy is the hope that early intervention will improve the outcome in the best cases, this has been established by placebo-controlled, double-blind prospective clinical trials. For example, treatment of febrile episodes in neutropenic cancer patients with empiric antimicrobial therapy has been demonstrated to have impressive morbidity and mortality benefits even though the specific bacterial agent responsible for fever is determined for only a minority of such episodes. 

Campylobacter species are most commonly responsible for outbreaks of bacterial gastroenteritis in developed countries. The majority of die gastrointestinal Campylobacter infections do not require antibiotic treatment and are selflimiting. Where treatment is required, erythromycin is usually recommended. However, fluoroquinolones are often also used pending laboratory results, because they can cover additional bacterial pathogens and are better tolerated than erythromycin. 

The MAPK cascade in the plant s defense against bacterial pathogens is remarkably similar to the innate immune response triggered by bacterial lipopolysac-charide and mediated by the Toll-like receptors in mammals (Fig. 12-30b). Other membrane receptors use similar mechanisms to activate a MAPK cascade, ultimately activating transcription factors and turning on the genes essential to the defense response. 

These corrected values for the pKA of HNO (>11) and reduction potential of NO (< —0.7 V) demonstrate that HNO, rather than NO, is the predominant species in neutral solution and indicate that NO cannot be easily converted to NO- by simple outer-sphere electron transfer (Scheme 6), unlike the O2/O2 redox couple. The different potentials and concentrations of NO and O2 in cellular or physiological systems suggest that NO is essentially inert to reduction to NO in mammalian biology. Note that certain processes in bacteria are suggested to have sufficient potentials to reduce NO (165, 166), which may have some importance both to normal bacterial physiology, including nitrification and denitrification, and to antibacterial and pathogenic responses. 

The ability of dietary consumption of foods containing LAB to modulate immune responses has been thoroughly studied in animal models. Dietary consumption of LAB and Bifidobacteria strains have been shown to enhance protection against intracellular bacterial pathogens. Physiological responses have been shown to correspond with the cell-mediated immune responses that have the Thl cell bias. 

As an important membrane anchored molecule in Gram-negative bacteria that can activate the immune response, LPS and lipid A are largely needed for research to understand infection mechanism of bacterial pathogens. Methods for extraction and purification of LPS and lipid A still need to be modified to increase the yield and purity, so do the methods for analysis of LPS. 

Salmonella enterica (S. enterica) is a rod-shaped Gram-negative facultative anaerobe and a prominent enteric bacterial pathogen capable of causing food- and water-related diseases. Several serovars of S. enterica are associated with human infection. The principle clinical diseases associated with Salmonella infection are typhoid fever and gastroenteritis. S. enterica serovars Typhi S. Typhi) and Paratyphi (,S. Paratyphi) are pathogenically exclusive for humans and are known to cause typhoid or enteric fever (Ohl and Miller, 2001). Typhoid fever is a systemic infection characterized by the development of fever, abdominal pain, enterocolitis, and occasionally, a maculopapular rash. The hallmark feature of typhoid fever is the presence of mononuclear cell infiltration and hypertrophy of the intestinal Peyer s patches and mesenteric lymphoidal tissue (Kraus et al., 1999 Ohl and Miller, 2001). There are approximately 20 million cases of typhoid fever worldwide each year, and this acute and often life-threatening infection is responsible for over 200,000 deaths annually (Crump et al., 2004). 

Another pathway is the fatty acid hydroperoxidase lyase (HPL) pathway. This pathway produces C6-aldehydes and C12-oxo acids. 2 C6-volatiles, including ( )-2-hexenal, (Z)-3-hexenal, hexanal, as well as their corresponding alcohols or esters, are produced from mechanically wounded plant tissue.197,203 C6-aldehydes are also formed during hypersensitive response to infection by bacterial pathogens, after insect feeding, and after exogenous application ofJA.204,205 As already shown in this chapter, some of C6-volatiles are known to be attractants of parasitoids and predators. 

The oxidation of thiol groups disrupts redox balance (deflned later in this chapter), which can set into motion a cascade of events, such as apoptosis, oxidant production, and increased activity of redox-regulated transcription factors (e.g., nuclear factor kappa beta [NF-kB]). The occurrence of OS is not isolated to the vesicant class of weapons of mass destmction (WMD). Radiation (Kang et al., 2006), bacterial infections (e.g., anthrax) (Hanna et al., 1994 Kuhn et al., 2006), viral infections (e.g., influenza) (Ghezzi and Ungheri, 2004), and ricin (Kumar et al., 2003 Suntres et al., 2005) exposures also induce OS as part of the host pathogen response, which is acute inflammation. 

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